A tattoo is a permanent body modification made by inserting pigment or ink into the layers of skin to change the skin's normal pigmentation for decorative purposes or other reasons. The tattooing process involves the injection of pigment into the skin's dermis, the layer of connective tissue underlying the outer epidermis. After initial injection, pigment disperses throughout a homogeneous damaged layer down through the epidermis and upper dermis, in both of which the presence of foreign material activates the immune system's phagocytes to engulf the pigment particles. As healing proceeds, the damaged epidermis flakes away (eliminating surface pigment) and is replaced, while granulation forms deeper in the skin, which is later converted to connective tissue by collagen growth. This mends the upper dermis, where pigment remains trapped within fibroblasts, ultimately concentrating in a layer just below the dermis/epidermis boundary. Its presence there is stable, but in the long term (decades) the pigment tends to migrate deeper into the dermis, accounting for the degraded detail of old tattoos.
Many different dyes, inks and pigments and combinations typically are used in tattoos. They range from inorganic materials like titanium dioxide and iron oxides to carbon black, azo dyes, and acridine, quinoline, phthalocyanine and naphthol derivates, dyes made from ash, and other mixtures. Amateurs use any available vegetable or mineral for tattoos. The current trend for professional tattoo pigmentation utilizes a variety of acrylonitrile butadiene styrenes (ABS plastic) as a colorant. When ground down to an average diameter of slightly less than 1 micrometer, ABS plastics create tattoo pigments that are less likely to fade or blur over time than the traditional pigments. The tattoo dye can also contain non colorants, including but not limited to arsenic, cadmium, lead, nickel, antimony, chromium and cobalt. Common ingredients of red-coloured inks are mercury and cadmium; yellow-coloured inks commonly contain lead, cadmium and zinc. Orange-coloured inks usually cadmium. Common ingredients of green-coloured inks are lead, chromium and copper; and white inks commonly contain lead, zinc and barium.
According to FDA Consumer Health Information, “Think Before You Ink: Are Tattoos Safe?” (October 2009), No tattoo pigments are FDA approved; some are even repurposed printer inks and pigments suitable for automobile paint. “Removal is time-consuming, costly, and doesn't always work.” FDA warns: do not buy or order online do-it-yourself tattoo removal products. These acid-based products are not FDA-approved and can cause bad skin reactions.”
Seldom are any FDA-approved dyes used for tattoos. At best, the dye may be approved for cosmetic use—a surface application, not an injection. A variety of serious, even life threatening problems have been reported. In Europe many of the azo pigments, such as red PR 22, are not even allowed in cosmetics since they frequently react to produce carcinogenic compounds. The use of mercury, cadmium and other heavy metals can cause poisoning. Other case reports have disclosed cutaneous pseudolymphoma, granulomatous reaction, allergic reactions, pseudodepitheliomalous epidermal hyperplasia and even skin cancer.
The most common method of tattooing utilizes an electric tattoo machine, which inserts ink into the skin via a group of needles that are attached to an oscillating unit. The unit rapidly and repeatedly drives the needles in and out of the skin, usually 80 to 150 times a second. A small tattoo of simple design might take fifteen minutes to complete; whereas, a more elaborate design may require multiple, lengthy sessions.
Recently, cosmetic tattoos have become increasingly popular for adorning eyebrows and eyelids and have greatly expanded the market. It is estimated that as many as 4 in 10 citizens in the US have at least one tattoo. With such increased popularity comes an increased need for tattoo removal. Many of these tattooed individuals (reportedly ranging from about 14-21% of tattoo wearers) at some point wish to have their tattoo removed for one of many reasons. Sometimes there are medical reasons: Amateur tattoos may result in mercury poisoning; allergies to ink may arise. Many more are personal reasons. For example, an individual may have impulsively gotten a tattoo and now regrets that decision. Alternatively, a change in life circumstances may motivate the desire to have a tattoo removed. For example, an individual tattooed with the name or image of a spouse or lover may become estranged from that individual. Even if a tattooed individual desires to keep a tattoo, outside influence may motivate the decision to have it removed. A tattoo in an area of the body not covered by clothing such as the face, neck, hands or lower arms may make securing employment in certain professions more difficult. People leaving gangs often want to have their gang tattoos removed, to avoid confrontations with their former gang members and opposing gangs.
Current treatment options for tattoo removal include a variety of lasers, dermabrasion, salabrasion (abrasion with salt), surgical excision, cryotherapy and tattoo removal topical creams and lotions. Do-it-yourself topical creams cannot penetrate the epidermis to the layer with tattoo pigments embedded in cells, so how they work is not clear; they require frequent, even daily applications over weeks and months and often no change is seen. Some treatments may be effective; they may be expensive, time consuming, and painful. The more effective home treatments require dermabrasion with abrasive salty pastes that remove outer layers of skin in large patches. In some cases, such treatments also may result in cosmetically undesirable scarring.
One of the more effective tattoo removal treatments is a laser surgical technique in which the tattooed area is irradiated with a high-energy, pulsating laser beam. The tattoo ink pigments absorb a portion of the laser radiation. As a consequence, the pigment particles become sufficiently hot (and painful) that they decompose into smaller fragments. In the process, the cellular integrity of the surrounding dermal cells may be destroyed. A single laser treatment usually produces some fading of the tattoo because it sets up an immune reaction that drains some of the pigment fragments into the lymphatic system to reside in the lymph nodes; however, most pigment fragments become re-engulfed by still intact dermal cells and so remain visible. In nearly all cases, patients are not satisfied with the results of the first laser treatment, and they must return for numerous additional treatments. In the meantime, the laser has changed the color of some ink pigments, e.g., white or red to black, worsening the appearance for months. This change of color signals changes in the dye molecules and breaking of internal bonds into smaller molecules, some of which are toxic.